Your PC is under attack!

At first, the signs are subtle: Your computer is slower than usual, something is different about your browser, occasionally you're redirected to an unfamiliar Web site for no apparent reason.
When you finally figure out the problem, you discover that someone has been tracking every keystroke on your keyboard for days while using your PC's resources to maintain a network that researches extraterrestrial life. Adding insult to injury, you find that your 8-year-old son agreed to the whole mess to get some software given away online...